Clutch assemblies and piston seal assemblies for use in automotive transmissions are well known. Known piston seal assemblies are disclosed in U.S. Patent Application No. 2012/0161400, which is incorporated by reference herein as if fully set forth. The known assemblies generally include a disc-shaped piston, a retaining plate, and seal. The piston moves in the axial direction along a housing or a shaft via hydraulic fluid pressure, and the seal is designed to prevent leakage of the hydraulic fluid during movement in one direction, and is allowed to axially shift during movement in the opposite direction to allow flow of the hydraulic fluid past the seal. However, in these prior known arrangements, applicants have discovered that the seal can fail due to extrusion into a gap between the piston and the plate, and cause the piston seal assembly to malfunction.